Question: If $x \oplus y = 2x-6$ and $x \boxdot y = x-4y$, find $4 \oplus (5 \boxdot -2)$.
Solution: We don't need to find $5 \boxdot -2$ because $x \oplus y$ depends only on the left operand. Find $4 \oplus y$ $ 4 \oplus y = (2)(4)-6$ $ \hphantom{4 \oplus y} = 2$.